With 42,000 people left on the wait list, this year's event is the largest of its kind in North America - and with the tragic terrorist attack in Barcelona fresh on everyone's mind, police and event organizers weren't taking any chances with security.

Co-host Natanya Dibona said, "Homeland security instituted procedures where we block people off in the street. Here it's with our buses and police vehicles. We feel very safe that we've secured all our areas."

Inside is dinner, games and dancing.

A couple even got engaged tonight.

Elizabeth Livingston of Rittenhouse said, "Here you have to bring your inner child...It's a playground for everyone."

Emily Griesing of Center City said, "That's the whole fun of it. Everything is so structured in everything we do, it's nice to have something be up to someone else, be spontaneous because often we don't do that."